This invention relates to automatic machinery and more particularly to automatic machinery for handling cloth and similar flexible materials.
There have been many attempts to devise methods by which flexible materials may be handled automatically. In general, it has proven relatively easy to handle a material such as cloth while it remains in its uncut form. However, once material has been cut into small or any sort of irregular shape, its light weight, flexibility, stretchability, surface texture, and other characteristics make it very difficult to handle in a useful manner. Because of its high labor intensity and the high cost of that labor, the sewing industry is especially ready for such automatic machinery. There are special purpose machines on the market each of which is adapted to accomplish one specific sewing operations over and over. Such machines are very expensive and suited to only the limited special purposes for which they were designed.
To broaden the range of operations, attempts are being made to build robots which may be programmed to perform the many operations of a human operator of a sewing machine. One of the main difficulties has been in providing a device with extreme sensitivity of touch and many degrees of freedom which is capable of simulating the human hand. To date there has been no hand simulator (called an "end effector") found practical to replace the human operator's hands in the automatic sewing of the many types and qualities of materials which must be handled.
There have been devices which use needles adapted to project through a base into some portion of a layer of material in order to handle that material, e.g., see Canadian Apparel Manufacturer, pp. 11-18, June 1983, by Frank W. Paul. Theoretically, such a device will work but in actuality there are no industrial sewing machines using such devices because they cannot be made to work reliably. For example, needles have such a shape that they penetrate to essentially an unlimited depth in most materials. Consequently, the depth of penetration must be adjusted so that a particular needle penetrates only a selected thickness of the particular material with which it is to be used. If the adjustment is slightly off, then the needle penetrates either too deeply or too shallowly. If the needle penetrates too deeply, it may break or bend on the surface against which the material is urged; and the device ceases to operate. Alternatively, if the needle penetrates too shallowly, it is not able to secure the material and the device does not operate. (See statistics from above noted article.)
Moreover, needles must be adjusted for each particular thickness of material. For example, if it is desired to pick up a single layer of material and the needles of the end effector project too far, they pass through the piece of material and pick up more than the desired single layer. Thus, while the theory of using needles to handle flexible material such as cloth is quite good, the result is that such devices are unreliable; and the use of labor has been found to be cheaper.
It is, therefore, an object of this invention to provide an end effector which may be used with industrial robots for handling flexible materials.
It is another object of this invention to provide a device which will handle all types of flexible materials.
It is another object of this invention to provide a device which will handle materials in many different opeations.
It is an additional object of this invention to provide a device which will handle varying thicknesses of materials.
It is yet another object of this invention to provide a device which is capable of handling flexible material such as cloth inexpensively and rapidly.